Does a particular URL exist?
A difficult question and one there isn't a general answer to - but
you can check whether an http:// URL is readable which is often the
question that's being asked. With a URL such as a mailto:, the only
way to check whether it exists is to send an email to it and see if
you get an answer back from the address owner. You also need to
take care with testing like this to ensure that the user can't
enter local file URLs on your server and use it to check the
existance (or otherwise) of files / directories ....
Checking URL http://www.wellho.net/net/new.html
This URL s readable
Please enter a URL you would like to validate (existance check):
Note - in order to save myself the need to monitor the use of this script, I
have only loaded it here it its tested (HTML) form and the form just above will
not work. You are welcome AT YOUR OWN RISK to test the code that's presented
below on your own server. Unless you are very sure of what you are doing, I advise
you NOT to put this script onto a live Internet server
Copyright Well House Consultants
2005
Source code of this example:
<?php
if ($_REQUEST[url] != "") {
$result = 1;
if (! ereg("^https?://",$_REQUEST[url])) {
$status = "This demo requires a fully qualified http:// URL";
} else {
if (@fopen($_REQUEST[url],"r")) {
$status = "This URL s readable";
} else {
$status = "This URL is not readable";
}
}
} else {
$result = 0;
$status = "no URL entered (yet)";
}
?>
<html><head><title>Does a URL exist?</title></head>
<body bgcolor="white"><table width="600"><tr><td>
<h1>Does a particular URL exist?</h1>
A difficult question and one there isn't a general answer to - but
you can check whether an http:// URL is readable which is often the
question that's being asked. With a URL such as a mailto:, the only
way to check whether it exists is to send an email to it and see if
you get an answer back from the address owner. You also need to
take care with testing like this to ensure that the user can't
enter local file URLs on your server and use it to check the
existance (or otherwise) of files / directories .... <br /><br />
<?php
if ($result != 0) {
print "Checking URL <b>".htmlspecialchars($_REQUEST[url])."</b><br />";
}
print "$status";
?>
<br />
<hr />
Please enter a URL you would like to validate (existance check):
<form>The URL: <input name="url" /> and <input type="submit" /></form>
<hr />
Copyright <a href="http://www.wellho.net/">Well House Consultants</a>
<?= date("Y") ?><br /><br />
<b>Source code of this example:</b><br /><br />
<?= highlight_file($_SERVER[SCRIPT_FILENAME],1) ?>
</td></tr></table>
</body></html>
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